Art of gluing



Patented Feb. 21, 1933 UNITED STATES PATENT OFFICE HARRY GALQBER, OFLOCKPORT, NEW YORK, ASSIGNOR, IBY MESNE ASSIGNMENTS, TO

LAMINATING PATENTS CORPORATION, OF SEATTLE, WASHINGTON, A CORPORA- TIONOF DELAWARE ART OF GLUING .Applz'ication filed February 24, 1932. SerialNo. 594,857.

This invention relates to the art of gluing, and, more particularly, toprocesses for the formation of plywooc An object of the invention is toprovide an improved process for uniting a wood member and anothermember.

A further object is to provide an improved method for the formation ofplywood.

Uther objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the several steps and the relationand order of one or more of such steps with respect to each of theothers thereof, which will be exemplified in the process hereinafterdisclosed, and the scope of the application of which will be indicatedin the claims.

For a fuller understanding of the nature and objects of the inventionreference should be had to the following detailed description taken inconnection with the accompanying drawing, in which The figureillustrates somewhat diagrammatically a mode of procedure in accordancewith the invention.

The invention contemplates the provision of an improved procedure foruniting a memher composed of wood to a member formed of such material orother material. It is particularly adapted for the formation of plywoodcomposed of two or more substantial layers, at least one of which isformed of wood. It is to be understood that the term wood as used hereinincludes any porous material of a fibrous or cellular structure havingsufficient body to permit the adhesive to obtain a firm grip thereon.

Tn the formation of such a product the provision of an adhesive base indiscrete-particle form at the glue line, possesses a number ofadvantages and various proposals to this end have been made, as, forinstance, in various copending applications of Theodore Williams Dikeand others.

It is customary in the formation of plywood to place the assemblybetween pressure plates and to subject it to pressure, or to heat andpressure therein, in order to set the adhesive.

When the adhesive base is applied in discrete-particle form, manydifficulties occur in obtaining the proper degree of plasticization andpenetration before the final setting of the adhesive, and in properlycorrelating the plasticization and setting factors. The difficulties inobtaining sufiicient penetration are particularly marked in the use ofdifiicultly plasticizable material such as casein, soyabean flour, otheroil-seed flours, etc.

In accordance with the present invention a gluing procedure may becarried out in such a manner that these difliculties are reduced oravoided.

Certain of these difiiculties result from a premature setting of theadhesive before the same has been fully plasticized, i. e., brought intoa sufficiently fluid state to properly penetrate the pores of the wood,so that, when the adhesive sets. forces tending to separate the memberswill encounter resistance of a substantial body of the wood rather thanmerely the surface fibres which are easily pulled off. With a view toavoiding this and other difficulties, the invention contemplates theremoval of the assembly from the press after the formation of apreliminary bond sufficient to hold the members together while furtherplasticization and setting occur, and preferably discontinuing theapplication of heat and pressure at a time when a layer of substantiallyindependent particles remains between the members, (i. e., when there isbetween the members a layer of discretepar ticles of the adhesive whichpresent a substantially unbroken sandy appearance to the eye if themembers are separated), and also when a plasticizing liquid is stillpresent at the glue line.

The preliminary bond need be more than 2-1 blood albumin.

suflicient to hold the members together while the assembly is removedfrom the press and set. aside for further action. Such preliminar bondmay be formed by that portion of a iflicultly plasticizable,slow-setting adhesive, which is first plasticized and set, or, desirablyby a quick-setting adhesive included :n the adhesive base materialsupplied. Such quick-setting adhesive may desirably be an albuminousmaterial such, for example, as The conjoint use of blood albumin andsoya-bean flour, casein, or the like is disclosed and claimed in thecopending application of Theodore lVilliams Dike, Serial No. 455,978,filed May 28, 1930, and patented March 29, 1932, Patent No. 1,851,951,and no claim is made herein broadly to the conjoint use of suchmaterials.

As diflicultly plasticizable materials, reference may be made to casein,soya-bean flour, other oil-seed flours, etc. These are applied indiscrete-particle form, preferably in powdered form. The quick-settingadhesive is desirably supplied also in powdered form, but in certaininstances may be carried in a liquid vehicle.

A l quid, ordinarily water, is utilized in the plasticization of suchmaterial, and the liquid may be provded in any desired manner. Theinvention permits the liquid to exert its effect as the formation of thebond proceeds.

In accordance wfth the invention, moreover, a plasticization promoter isgiven an opportunity to exert its effect slowly while the plasticizationand setting of the adhesive proceeds. Caustic soda is the preferredexample of such a plasticization promoter. This material not onlyassists in the plasticization of the adhesive base, but also has adesirable effect on the fibres of the wood adjacent the glue line.promoting materials such as hydroxides of other alkali metals, or, insome instances, alkaline earth hydroxides, such as lime, or othermaterials may be utilized. Such a plasticization promoter maybe appliedor produced at the glue line in any manner which may be desirable in a;particular instance.

Preferably, in many instances, only a moderate heat is applied with thepressure, for example, heat in the neighborhood of 220 F. to 260 F. Byavoiding high heats too rapid action at the glue line is prevented.

It is to be understood that the term slowsetting adhesive, as usedherein, is designed to cover an adhesive, the setting of which whenapplied in discrete-particle form is relatively slow, regardless ofwhether the slowness of the setting is due to slowness in obtainingcomplete plasticization or for other reasons.

As examples of procedures which may be carried out in accordance withthe invention, reference is made to the following:

Three-ply panels may be formedof com- Other plasticizationmercially dryone-sixteenth inch birch veneer by supplying to one of each pair ofsurfaces water at the rate of 12 lbs. per thousand square feet of doubleglue line, soyabean flour at the rate of 24 lbs. per thousand squarefeet of double glue line, and 10% caustic soda solution at the rate of24 lbs. per thousand square feet of double glue line; forming anassembly; and placing the assembly in a hot plate press and applyingpressure in the neighborhood of 200 lbs. pressure per square inch, andheat of approximately 230 F., for 40 seconds. The assembly is thenremoved and set aside while the plasticization and setting of theadhesive at the warm glue lines continues, forming a strong, securebond.

Three-ply panels may be formed of commercially dry one-sixteenth, inchbirch veneer by applying to one of each pair of surfaces water at therate of 12 pounds per thousand square feet of double glue line, amixture of 80 parts of soya bean flour or powdered casein with 20 parts.of powdered dried blood at the rate of 24 pounds per thousandsquare-feet of double glue line, and a 10% sodium hydroxide solution atthe rate of 24 pounds per 1,000 square feet of double glue line; formingan assembly; and subjecting the assembly in a hot plate press topressure in the neighborhood of 200 pounds per square inch' and atemperature of 230 F. for thirty seconds; and then removing the assemblyfrom the press and permitting the plasticization and setting of theadhesive to proceed. -The blood in this case provides an especiallysecure clamp for'holding the v members together.

As above indicated, the blood may be in certain instances included inthe water applied, and may be so applied at a desired stage in theprocedure.

In the drawing there is exemplified a form of apparatus and procedurewhich may be utilized in carrying out the invention. There is shown aconveyor 10 above which is a disseminatin mechanism indicateddiagrammaticalTy at 11 and which may be of a form such as disclosed inthe copending application of Louis G. Merritt and Ericsson H. Merritt,Serial No. 542,257, filed June 5, 1 931. Ahead of and beyond thisdisseminating mechanism are spray means indicated diagrammatically at 12and 13 and which may be of the type disclosed in the copendingapplication of Ericsson H. Merritt and Richard W. Stanley, Serial No.535,822, filed May 8, 1931. In the use of such an apparatus woodensquares or plies 14 are disthence under the disseminating means 11whereby a powdered adhesive material, with or without the otheringredients in powdered and another member, which comprises form, isapplied thereto, and thence under the spray means 13 whereby thepowdered materials are wet down by a spraying liquid. T he squares 14may be disposed one on top of another and an additional square 15disposed on the uppermost surface, as indicated. A square 15 may bedisposed on square 14; and the partial assembly thus formed may bere-disposed on the conveyor 10 and moved under the mechanism 12, 11 and13, or may be disposed on another conveyor and passed under similarmeans, and an additional square disposed thereon. Other procedures maybe followed. A twoply or multiple-ply assembly thus formed may beinserted in the press indicated at 16 as a conventional plywood press,and subjected to heat and pressure, or may be subjected to pressure andheat,

Since certain changes may be made in carrying out the above processwithout departing from the scope of the invention it is intended thatall matter contained in the above description shall be interpreted asillustrative and not in a limiting sense.

It is also to be understood that the following claims are intended tocover all of I the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secureby Letters Patent, is:

1. The process of uniting a wood member and another member, whichcomprises providing between said members adhesive-base material indiscrete-particle form, applying heat and pressure for a periodsufiicient to form a preliminary bond between the members, discontinuingthe application of heat and pressure while a layer of substantiallyindependent particles remains between the members, and permitting theplasticization and setting of the adhesive material to continue.

2. The process of uniting a'wood member roviding between said membersadhesivease material in discrete-particle form, applying 1 heat andpressure for a period sufiicient to form a preliminary bond between themembers, a liquid being present, discontinuing the application of heatand pressure while a layer of substantially independent particlesremains between the members and while liq uid is still present, andpermitting the plasticization and setting of the adhesive material tocontinue. I

3. The process of uniting a wood member, and another member, whichcomprises providing between said members vproteinous adhesive-basematerial in discrete-particle form, applying heat and pressure for aperiod suflicient to form a preliminary bond between the members,discontinuing the application of heat and pressure while a layer ofsubstantially independent particles remains between the members, andpermitting the plasticization and setting of the adhesive material tocontinue.

4. The process of uniting a wood member and another member, whichcomprises providing between said members difiicultly plasticizableadhesive-base material in discreteparticle form, applying heat andpressure for a period sufficient to form a preliminary bond between themembers, a liquid being present, discontinuing the application of heatand pressure while a layer of substantially independent particlesremains between the members and while liquid is still present, andpermitting the plasticization and setting of the adhesive material tocontinue.

5. The process of uniting a wood member and another member, whichcomprises providingbet'ween said lnembers difiicultly plasticizableadhesive-base material in discreteparticle form and a plasticizationpromoter, applying heat and pressure for a period sufficient to form apreliminary bond between the members, a liquid being present,discontinuing the application of heat and pressure while a layer ofsubstantially independent particles remains between the members, and. I

while liquid is still present, and permitting the plasticization andsetting of the adhesive material to continue.

6. The process of uniting a wood member and another member, whichcomprises providing between said members powdered casein and aplasticization promoter,applying. heat and pressure for a periodsufficient to form a preliminary bond between the members, a liquidbeing present, discontinuing the application of heat and pressure whilea layer of substantially independent particles remains between themembers and while liquid is still present, and permitting theplasticization and setting of the adhesive to continue.

'7. The process of uniting a wood member and another member, whichcomprises providing between said members soya-bean flour and aplasticization promoter, applying heat and pressure for a periodsuflicient to form a preliminary bond between the members, a liquidbeing present, discontinuing the application of heat and pressure whilea layer of substantially independent particles remains between themembers and while liquid is still present, and permitting theplasticization and setting oi the adhesive to continue.

4 bon base, the slow-setting adhesive base being in discrete-particleform and a softening liquid therefor being provided, applying heat andpressure for a period suflicient to form a preliminary bond between the.members, discontinuing the application of heat and pressure, andmaintaining the members free from pressure while the plasticization andsetting of the slow-setting adhesive proceeds.

9. The process of uniting a wood member to another member involving theuse of a slow-setting adhesive, which comprises providing between themembers a slow-setting adhesive base and an albuminous adhesive base,the slow-setting adhesive base being in discrete-particle form and asoftening liquid therefor being provided, applying heat and pressure fora period suflicient to form a preliminary bond between the members,discontinuing the application of heat and pressure, and maintaining themembers free from pres-' sure while the plasticization and setting ofthe slow-setting adhesive proceeds.

10. The process of uniting a wood member to another member involving theuse of a slow-setting adhesive, which comprises providing between themembers a slow-setting adhesive base and blood albumin, both of saidadhesive bases being applied in powdered form, applying heat andpressure for a period sufficient to form a preliminary bond between themembers, discontinuing the application of heat and pressure, andmaintaining the members free from pressure while the plastieization andsetting of the slow-setting adhesive proceeds.

11. The process of uniting a Wood member to another member involving theuse of a slow-setting adhesive, which comprises providing between themembers a slow-setting adhesive base and blood albumin, the slowsettingadhesive being applied in discreteparticle form and the blood albuminbeing applied in a liquid vehicle, applying heat and pressure for aperiod suflicient to form a preliminar Y bond between the members,discontinuing the application of heat and pressure, and maintaining themembers free from pressure while the plasticization and setting of theslow-setting adhesive proceeds.

12. The process of uniting a wood member to another member, whichcomprises providing between the members adhesive-base material indiscrete-particle form, applying to the members pressure and a moderateheat for (periods sufiicient to form a preliminary discontinuing theapplication of heat and pressure while a layer of substantiallyindependent particles remains between the members, and permitting theplasticization and setting of the adhesive material to continue.

13. The process of uniting a wood member to another member involving theuse of :1.

slow-setting adhesive, which comprises providing between the membersdifiieultly plasticizable slow-setting adhesive-base material indiscrete-partic1e form and a plasticization promoter and a quick-settingadhesive, applying to said members pressure and a moderate heatsufficient to form a preliminary bond between the members, a liquidbeing present, discontinuing the application of heat and pressure, andmaintaining members free from pressure while the plasticization andsetting of the slow-setting adhesive proceeds.

14. The process of uniting a wood member to another member involving theuse of a slow-setting adhesive, which comprises providing between themembers soya-bean flour and a plasticization promoter and an albuminousadhesive base, applying to said members pressure and a moderate heatsufiicient to form a preliminary bond between the members, a liquidbeing present, discontinuing the application of heat and pressure, andmaintaining members free from pressure while the plasticization andsetting of the slow-setting adhesive proceeds.

15. The process of uniting a wood member to another member involving theuse of a slow-setting adhesive, which comprises providing between themembers powdered casein and a plasticization promoter and an albuminousadhesive base, applying to said members pressure and a moderate heatsuflicient to form a preliminary bond between the members, a liquidbeing present, discontinuing the application of heat and pressure, andmaintaining members free from pressure while the plasticization andsetting of the slow-setting adhesive proceeds.

16. The process of forming plywood comprising thin outer plies, whichcomprises providing adhesive-base material in discreteparticle formbetween the members and forming an assembly, applying heat and pressureto the assembly for a period sufficient to form a preliminary bondbetween the members, discontinuing the application of heat and pressureWhile a layer of substantially independent particles remains at eachglue line, and maintaining the assembly free from pressure while theplasticization and setting of the adhesive material continues.

1?. The process of forming plywood comprising thin outer pli'es, whichcomprises providing diflicultly plasticizable adhesive-base material indiscrete-particle form between the members and forming an assembly,applying heat and pressure to the assembly for a period in theneighborhood of thirty to forty seconds, discontinuing the applicationof heat and pressure, and maintaining the assembly free from pressurewhile the plasticization and setting of the adhesive proceeds,

18. The process of forming plywood comprising thin outer plies, whichcomprises pro

